This invention relates to firearms.
The present invention is primarily concerned with the production of lightweight firearms, particularly revolvers, and deals more specifically with improvements in firearm frame and barrel assemblies of a type having a two-piece barrel which includes an inner barrel sleeve made of high-alloy steel and an outer barrel shroud made from a substantially lighter or less dense material, such as aluminum. Such two-piece barrel assemblies have been heretofore employed in the production of lightweight firearms. However, where gun design criteria requires that the outer shroud cover the inner barrel sleeve along substantially the entire length of the sleeve, the inaccessibility of the sleeve posses an assembly problem. In accordance with one successful solution to the assembly problem, the barrel pieces are assembled with a press fit and further secured in assembly by an anaerobic adhesive to form a unitary structure which is then assembled to a gun frame by the conventional process of engaging timed threadsxe2x80x94a process which has been used in gun manufacture for about a century.
Since the barrel shroud usually includes a sight or at least provision for sight mounting, it is essential that the sight or its mounting means be properly aligned with the gun frame. In accordance with the aforesaid assembly method, torque must be applied to the gun barrel assembly to threadably secure it to the gun frame with proper sight alignment and is dependent upon thread timing, which makes it difficult to maintain uniform assembly torque. In some instances, frame and barrel parts must be individually fitted to obtain a desired result. Further, sight alignment relative to the frame must be externally gauged at assembly, all of which adds to the cost of producing a firearm.
Where a fully shrouded barrel is provided, it is conventional to apply assembly torque directly to the outer surfaces of the barrel shroud to secure the barrel assembly to the frame. This procedure can damage the surfaces to which torque is applied resulting in cosmetic defects and surface deformations. The present invention is concerned with the aforedescribed problems.
Accordingly, it is the general aim of the present invention to provide an improved lightweight barrel and frame assembly for a firearm which permits substantially uniform assembly torque to be specified and maintained in effecting assembly of a barrel subassembly with a gun frame during manufacture and which discourages a gun user from attempting disassembly of the barrel subassembly from the frame. It is a further aim of the invention to provide an improved barrel and frame assembly whereby sight frame alignment is automatically attained during assembly, making it unnecessary to gauge sight alignment after assembly. Yet another aim of the invention is to provide an improved method and tool for assembling a lightweight two-piece barrel to the frame of a firearm without risk of damaging the external surfaces of the firearm during the assembly process.
In accordance with the present invention an improved firearm frame and barrel assembly is provided which includes a frame member, a barrel shroud member having a shroud bore and an abutment therein, and a generally cylindrical barrel sleeve having a rifled bore including spiral rifling grooves and extending into the barrel shroud bore and threadably engaged with the frame. An alignment means may be provided for retaining a sight position on the shroud member in a predetermined condition of alignment with the frame member during assembly of the shroud member with the frame member and when the shroud member is secured in assembly with the frame member by a bearing surface on the barrel sleeve in engagement with the abutment within the shroud bore. The barrel sleeve has a muzzle portion disposed within and complementing a forward end portion of the shroud bore and terminated by a generally radially disposed and forwardly facing substantially smooth uninterrupted annular muzzle surface surrounding a muzzle end of the rifled bore. The portion of the barrel sleeve member which projects axially forward from the frame member is concealed along its entire axial length within the shroud member. An assembly tool having spiral lands which engage and complement the spiral rifling grooves in the rifled bore is employed to assemble the frame and barrel assembly in accordance with a method of the present invention.